Elaborate diagram for electrical commands, where to start?

The drawing of electrical diagrams is not really an easy task, for this reason, it is necessary for some knowledge to be developed. Therefore, in this article, you will receive tips on how to develop skills in drawing electrical diagrams. Come on, guys!

It is important that you understand and know how to differentiate the types of existing electrical diagrams, which are basically four types, the multifilament, functional, single-line and three-wire.

To start the project, collect as much information as possible, such as: types of loads or motors to be used, what is the purpose of the electrical circuit, mains voltage supplied, what the customer requires in the circuit, everything in as much detail and types of materials to be used.

Diagrams that refer to electrical commands two types of diagrams are required, one for loads and the other for commands.

Load diagram

As the name implies, the load diagram is responsible for containing all connections and information related to the loads, which are usually the motors.

The information that should be contained in this diagram are indications of the supply busbars (L1, L2, L3, N, PE), voltage level, the current capacity of the busbars, information on the types of protection components, contactors, information on characteristics of charges and caption with company stamp information.

Three-wire diagram for electrical controls, showing the connection of a single-phase motor.

Command diagram

The command diagrams are responsible for containing information on the equipment for driving loads and / or motors, such as: whether they will be timed, whether they will be activated by contractors, in addition to containing information such as protection, pushbuttons, beacons, power source (L1 L2 L3), contacts, whether they will be normally closed or open, timers, PLC, soft starter, frequency inverters if applicable, protection relays, input and output terminals.

In diagrams of electrical controls, it is important that you leave well defined and clear all the information so that the professional who will perform the assembly has no doubts.


Based on the information made available to the designer, start the drawing by feeding the load diagram, which has the letter L as its symbol, then place the first protection that is symbolized by the letter F, then represent the contactor (K), relay of protection, but followed by a number and finally the motor (M). If it is a reversing command, do not forget to define the number and order of the contactors. After the load diagram is ready, proceed to the command diagram.

In the command diagram, it is necessary to demonstrate the contacts normally open and closed with their respective symbols and connections.

With all the necessary information for the development of the command diagram in mind, start your drawing by the power supply (L), then go through the protection (F) of the command circuit, which are circuit breakers or fuses, afterward the button connections will be made ( S) in which the NC / NO contacts together with auxiliary contacts of the contactor. Then draw the connections for the contactor coils (K) and terminals (A1 and A2). At the end of the command diagram, go through the flags (H).

Currently, we can count on software that helps us to simulate and correct errors, which does not dispense with knowledge in relation to the operation of equipment and project development.

For a quality project to be developed, it is important that the professional is up to date and performs the service in accordance with the standards, as he will have to dimension the entire circuit, cables, protections, contactors, always observing the contacts, symbols and various representations.